| Marinated dried bean curd is made from soybeans through grinding,boiling,pulping and pressing processes,and then reprocessed into bean curd,by stewing,seasoning,baking and other processing links to get the product.Marinated dried bean curd are not only rich in nutrients and mineral elements,but also have a unique stewed flavor.With the improvement of people's life quality and the expansion of leisure food demand,how to stabilize the flavor of marinated dried bean curd bittern and industrialize the production process has become an urgent problem to be solved.The problems such as long time consumption and unstable product quality limit the large-scale production.Therefore,based on the optimization and improvement of the traditional technological process,this paper comprehensively evaluated the sensory,microbiology,nutrition and other aspects of the marinated dried bean curd;to explore the effects of different processing techniques on volatile flavor substances of marinated dried bean curd;to explore the effects of different processing techniques on the formation of marinated dried bean curd protein gel;to provide basic data and theoretical support for the industrialization,market production and promotion of marinated dried bean curd.The results are as follows:1.Study on new process of marinade and optimization of process parameters:the traditional production and processing method of dried bittern beans was improved,the process of impregnating white embryo in the marinade for 8~12 h in the traditional process was changed to the process of impregnating tofu pudding in the marinade for 10 min and then pressing,so as to improve the production efficiency.The interior color of the new dried bean curd is uniform,with good halogen flavor and texture.The optimum process parameters were obtained by orthogonal optimization of the new process: optimize the new process and determine the best production plan.After optimizing the production conditions by single factor test and orthogonal test,the optimal solution was determined to be the impregnation time of 10 min,the ratio of marinade to tofu pudding impregnation was 1:1,and the salt content was 1.5%,the optimal solution was the best,the sensory score of the optimized scheme was as high as 90.42 points,golden color,outstanding flavor,delicate taste,more chewing.2.Effects of new marinade technology on the taste quality of marinated dried bean curd:the sensory quality of the new marinated dried bean curd has been greatly improved and is more popular among the public.There was no significant difference in protein content and fat content,but the salt content was greatly reduced from 36.35 mg/100 g to 24.01 mg/100 g.The color difference analysis showed that the internal brightness value L* of traditional dried bean curd was 59.50±2.73,which was significantly higher than the internal brightness value L*43.13±0.73 of the modified dried bean curd.The internal red and green value a* of traditional marinated dried bean curd was lower than that of the surface of traditional marinated dried bean curd and the new marinated dried bean curd,while the color difference between the inside and outside of the new marinated dried bean curd was not significant.This indicates that there is a significant color difference between inside and outside of the traditional marinated dried bean curd,while the new process solves the problem of production and different color.The cohesion,adhesiveness and chewability of the new marinated bean were significantly better than that of the traditional.The free amino acids in marinated bean were analyzed,The content of essential amino acids in marinated dried bean curd was increased(17.52 %)compared with that in traditional marinated bean.There was no difference in restricted amino acid content.From the analysis of flavorful amino acids,the new marinated dried bean curd was significantly optimized,and its umami amino acid > bitter amino acid > sweet amino acid > aromatic amino acid.The content of sulfur-containing amino acids in new marinated dried bean curd was the highest(0.54%),the higher the content of sulfur-containing amino acids,the stronger the gel.3.Effect of marinade on the flavor quality of marinated dried bean curd:the aroma components of marinated dried bean curd are mainly composed of alcohols,aldehydes,hydrocarbons,furans,phenols and other substances.A total of 72 volatile flavor substances were detected in tofu,117,117 and 118 volatile flavor substances were detected in marinade,traditional marinated dried bean curd and the new.The total content of aldehydes was 18.50% in the marinade,9.25% in the traditional marinated dried bean curd and 11.49% in the new marinated dried bean curd.The trans cinnamaldehyde marinade contained in cinnamon contained 11.14 %,the traditional curd contained 0.37 %,and the new marinated dried bean curd content increased to 0.50 %.The content of ketone was 3.34 % in traditional marinated dried bean curd and 7.99 % in new marinated dried bean curd.As the main ingredient of fennel,the content of marinated dried bean curd increased from 1.07 % to 1.21 %.The content of other volatile flavor substances in traditional marinated dried bean curd was 3.04% and that in new bean curd was 6.63%.The content of anisole,the main ingredient of star anise,in traditional marinated dried bean curd was 0.18%,and that in the new marinated dried bean curd was 0.33%.The new process can retain the characteristic aroma components of the marinade more effectively.4.Effects of new halogenation process on the formation of soybean dry gel system:SDS gel electrophoresis analysis was conducted on soybean meal,soybean milk,white bean curd,traditional marinated dried bean curd and new marinated dried bean curd.The composition of them proteins was basically the same.The 7S and 11 S subunit bands are clearly visible,the content of 11 S subunit in traditional marinated dried bean curd was 39.39 %,and that in new marinated dried bean curd was 57.49 %,which increased significantly.The new marinated dried bean curd 11S/7S was 1.82,while the traditional marinated dried bean curd 11S/7S was only 1.03.The protein solubility of soybean meal,soybean milk,white bean curd,traditional marinated dried bean curd and new marinated dried bean curd were analyzed.The solubility of white bean curd,traditional marinated dried bean curd and new marinated dried bean curd was less than that of soybean meal and soybean milk,this demonstrates that soy protein aggregates and denatures during the preparation of bean curd.After soybean became soybean milk,hydrogen bond force,disulfide bond force and hydrophobic interaction were strengthened.but the disulfide bond force and hydrophobic interaction decreased after soybean became bean curd.The microstructure of the bean curd was analyzed,the surface of the white bean curd was relatively smooth,the pore diameter was small,the surface of traditional marinated dried bean curd is rough,with a large number of flocculent and clumpy,large voids and uneven.Compared with marinated dried bean curd,the surface of the new marinated dried bean curd is smoother,with less protein fracture surface,no clumps and flocculent,and the pore size is smaller.To sum up,the new marinade technology,on the basis of maintaining the excellent physical and chemical quality of marinated dried bean curd,enriches the product flavor,shortens the production time and improves the product quality. |
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